212
GC/MSD interface
The GC/MSD interface is a heated conduit into the MSD for the capillary
column. It is bolted onto the right side of the vacuum manifold, with an
O-ring seal. A channel machined into the flange for the seal provides thermal
isolation between the heated interface and the O-ring and manifold. The GC/
MSD interface is covered by a protective cover which should be left in place.
One end of the GC/MSD interface passes through the side of the gas
chromatograph and extends into the GC oven. This end is threaded
(thread size is 10
× 32), allowing connection of the column with a nut and
ferrule. The other end of the GC/MSD interface fits into the ion source. The
last two millimeters of the capillary column extend past the end of the guide
tube and into the ionization chamber.
The GC/MSD interface is heated by an electric cartridge heater. The heater
is powered and controlled by Thermal Aux #2 heated zone of the HP 6890
Series GC. The GC/MSD interface temperature can be set from the MSD
ChemStation or from the keypad of the gas chromatograph. A sensor (ther-
mocouple) in the GC/MSD interface monitors the temperature.
The GC/MSD interface should be operated in the 250° to 350°C range.
Subject to that restriction, the GC/MSD interface temperature should be
slightly higher than the maximum GC oven temperature, but
never higher
than the maximum column temperature.
See Also To install a capillary column using the installation tool, 28
To install a capillary column without the installation tool,26
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